Businesses using Carbonite often rely on it to protect their Microsoft 365 (M365) data, including emails, OneDrive files, SharePoint, and Teams. However, backup failures or errors can occur, putting critical business data at risk.

This guide details common Microsoft 365 backup issues with Carbonite and provides practical solutions to maintain reliable cloud protection.

Common Causes of Microsoft 365 Backup Issues

1. Authentication or Account Permission Problems

   • Backup requires proper admin credentials with access to all M365 services.

2. Expired or Invalid OAuth Tokens

   • Carbonite uses OAuth for secure access; expired tokens can prevent backups.

3. Network or Connectivity Issues

   • Unstable internet or blocked ports can interrupt Microsoft 365 data backup.

4. Service-Specific Errors

   • SharePoint, OneDrive, or Teams may have service-specific errors that block backups.

5. File or Folder Restrictions

   • Large files, restricted file types, or unsupported SharePoint structures may fail to back up.

6. License Limitations

   • M365 subscription or Carbonite plan may have device, mailbox, or storage limits.

7. Corrupted Backup Settings

   • Misconfigured backup policies can prevent specific services from being backed up.

Step-by-Step Solutions for Microsoft 365 Backup Issues

1️⃣ Verify Admin Credentials

• Ensure the account used for M365 backup has Global Admin or appropriate permissions.

• Reauthenticate the account in Carbonite if needed.

2️⃣ Refresh OAuth Tokens

• Log in to Carbonite → Navigate to Microsoft 365 backup settings → Reauthorize access.

• Expired or revoked tokens often cause backup failures.

3️⃣ Check Network Connectivity

• Ensure reliable internet with unrestricted access to Microsoft 365 services.

• Verify that firewalls, proxies, or VPNs are not blocking Carbonite servers.

4️⃣ Examine Service-Specific Errors

• Check Carbonite logs for errors related to Exchange Online, OneDrive, SharePoint, or Teams.

• Resolve service-specific errors, such as missing folders, permission issues, or locked files.

5️⃣ Review File and Folder Limits

• Ensure files do not exceed maximum supported size for Microsoft 365 services.

• Avoid unsupported file types or folders with overly complex structures.

6️⃣ Confirm License and Storage Limits

• Verify that the Carbonite plan supports all M365 users and mailboxes you want to back up.

• Ensure Microsoft 365 subscription covers the mailboxes, SharePoint sites, and OneDrive accounts being backed up.

7️⃣ Reconfigure Backup Policies

• Review existing backup policies in Carbonite for Microsoft 365.

• Adjust settings to ensure all intended mailboxes, sites, and folders are included.

8️⃣ Monitor Backup Logs

• Carbonite logs provide detailed error codes and messages for Microsoft 365 backup failures.

• Identify recurring issues and apply recommended fixes.

9️⃣ Contact Carbonite Support

• If issues persist:

  • Provide M365 tenant details, Carbonite plan, admin account info, and backup logs.

  • Support can verify OAuth tokens, troubleshoot service-specific errors, and assist with policy configuration.

Best Practices for Microsoft 365 Backups

• Use a dedicated admin account for Carbonite backups.

• Monitor token expiration and reauthorize periodically.

• Schedule backups during off-peak hours to reduce service load.

• Verify backup logs regularly to catch failed mailboxes or services.

• Maintain a clear record of backup policies, license limits, and service coverage.

Tips to Prevent Microsoft 365 Backup Issues

• Always use an admin account with sufficient permissions.

• Keep OAuth tokens valid and refresh them when required.

• Ensure stable internet and network configurations for uninterrupted backup.

• Avoid including unsupported file types or overly large folders.

• Monitor backup logs and resolve errors promptly.

Frequently Asked Questions (FAQs)

Q1: Why are my Microsoft 365 backups failing in Carbonite?
Common causes include expired OAuth tokens, insufficient permissions, network issues, service-specific errors, file/folder restrictions, or license limits.

Q2: Can I back up all Microsoft 365 services?
Yes, Carbonite supports Exchange Online, OneDrive, SharePoint, and Teams, but each requires proper configuration and permissions.

Q3: What should I do if a specific mailbox or OneDrive fails to back up?
Check permissions, file size limits, and service-specific logs. Reauthorize the account if OAuth tokens have expired.

Q4: Do I need to contact support for recurring M365 backup failures?
Yes, especially if authentication, policy, or service-specific errors persist despite troubleshooting.